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L. E. DODGE.

AUTOMATIC TRAIN CONTROL SYSIEM.

APPUCATION FILED SEPT. 7, 19KB. 1,361,694 Patented Dec. 7, 1920.

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FIG. 1

INVENTOR 5, (9%

L. E. DODGE.

AUTOMATIC TRAIN CONTROL SYSTEM.

APPLICATION FILED SEPT. 7. 1916.

1,361,694;- Patentad Dec 7,, 19%" 4 SHEETS-SHEET 2.

Patented Dec. 7

L. E. DODGE.

AUTOMATIC TRAIN CONTROL SYSTEM.

APPLICATION FILED SEPT. 7. 1916.

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AUTOMATIC TRAIN CONTROL SYSTEM.

APPLICATION FILED SEPT. 7. 1910.

FFICE.

LYMAN IE. DODGE, Oli ROCHESTER, NEW YORK, ASSIGNOB T0 GENERAL RAILWAY SIGNAL COMPANY, OF GATES, NEW YORK, A CURPORATION 013 NEW YGRK.

AUTOMATIC TRAIN-CUNTRUL SYSTEM.

actose.

Application filed September 7, 1916.

T0 aZZ w from it may concern Be it known that l, LYMAN E. DODGE, a citizen of the United States, and a resident of the city of Rochester, in the county of Monroe and State of New York, have invented a new and useful Automatic Train- Control System, of which the following is a specification.

This invention relates to systems for automatically controlling the speed of railway trains.

One of the principal objects of this invention is to devise a construction and arrangement of parts such that the speed of a train may be automatically controlled at different points in its travel and restricted to any desired speed.

A further object of the invention is to devise a system for automatically controlling the speed of railway trains in which the limiting speed for the train is determined by the fundamental units of time and distance.

A. still further object of the invention is to devise a speed control system for railways such that the speed of a train may be controlled at different points in its travel in accordance with the location of other trains and also in accordance with the location of fixed hazards.

A still further object of the invention is to devise a speed control system for railways such that the engineer or motorman of a train will be given an opportunity to control the speed of the train himself and will be aided in this endeavor by being informed of the limiting speed for the train and the actual speed of the train at different points in its travel.

Uther objects and advantages will appear as the description of the invention progresses, and the novel features of the invention will be particularly pointed out in the appended claims.

In describing the invention in detail, reference is had to the accompanying drawing, wherein l have illustrated a preferred physical embodiment of my invention, and wherein like characters of reference designate corresponding parts throughout the several views, and in which:

Figure l is a diagrammatic view of the parts of a train control system embodying the invention which are carried by the train;

2 is a transverse section taken substantally on the line 2-2 in Fig. 1 and looking Specification of Letters Patent.

Patented Dec. 7, 1920.

Serial No. 118,818.

in the direction indicated by the arrows; Fig. 3 is a diagrammatic view of a portion of a railway track equipped with the speed control system embodying the invention; Fig. 4- is a diagrammatic View of a portion of a railway track and shows track circuits forming part of this invention and curves indicating the manner in which the speed of the train may be controlled over the stretch of track shown; and Fig. 5 is a diagraminatic view similar to Fig. 4: showing another stretch of track along which certain conditions'are assumed to exist which require special speed restrictions.

Referring to Figs. 1 and 2 of the accompanying drawing, the numerals 1 and 2 designate the track rails of the ordinary railway track which are supported upon ties 3 in the usual manner. The train or vehicle is shown diagrammatically as comprising a pair of wheels t5 connected by the usual axle 6. According to the particular embodiment of the invention illustrated it is assumed that the train is equipped with the well known system of air brakes which, as will be clearly understood by those skilled in the art, includes a train pipe 7. This train pipe '2' extends to a point near one of the track rails 2 where it terminates in a suitable valve 8 operated by an arm 9, it being understood that the engagement of the arm 9with an obstacle along the track causes an opening of the valve 8 and a resulting ap plication of the brakes.

Secured to the axle 6 is a beveled gear 10 which meshes with a beveled gear 11 connected to a flexible shaft 12. The flexible shaft 12 extends to a suitable speedometer or speed responsive device 13 provided with a suitable scale and pointer 1% by means of which the actual speed of the vehicle may be indicated. Supported on the vehicle in any suitable manner, as by means of supports 15, is a casing or frame K in which are supported two rollers 16 and 17. The roller 16 is connected to a beveled gear 18 which meshes with a beveled gear 19 fastened to the flexible shaft 12, so that as the vehicle travels and the axle 6 rotates, the roller 16 is turned. -Wound upon the rollers 16 and 17 is a continuous band 20 of heavy paper or similar material upon which are inscribed two rows of figures for the purpose explained hereinafter; and in the front of the casing K are out two openings 21 and 22 which expose one or the other of the above mentioned rows of figures. Supported in suitable bearings 23 secured to the casing K is a shaft 24: to which is secured a shutter 25, said shutter being arranged to cover one or the other of the openings 21 or 22, and a gear 26 is fixed to the shaft 24: and meshes with the rack teeth formed on a vertically movable bar 27 which is guided b suitable guides 28 secured to the casing l The upper end of the bar 27 is pivotally connected to a link 29, and this link is pivotally connected to the armature 30 of an electromagnet or relay 31.

The impulse for controlling the relay 31 may be transmitted from the track to the vehicle in various ways, but in the embodiment of the invention illustrated this impulse is obtained by the coperation electrically and mechanically of a contact shoe carried by the vehicle with suitable ramps or contact rails located at the desired points along the track. In the construction of the contact shoe shown in Fig. 1 a bracket 32 of wood or other suitable insulating material is carried by the vehicle, and a rod or plunger 33 is mounted in said bracket to move vertically and is urged to its normal lower position shown in Fig. 1 by a spring 34. To the upper end of the plunger 33 is secured a button 38 of suitable insulating material which serves to limit the downward movement of said plunger; and pivotally mounted between its ends on a support 35 secured to the bracket 32 is a contact lever 36, one end of which is provided with a counterweight 37 and extends to a point above the insulating button 38, and the other end of which is arranged to make electrical contact with a spring or arm 39 fastened to said bracket 32.

Supported in suitable guides fastened to the casing K are upper and lower rods 40 and d1 having pointers extending over the openings 21 and 22, respectively; and these rods 40 and 41 are connected at one end by a yoke l2 having a slot therein in which is disposed a thumb-nut 43 threaded onto a rod 44 fixed to the casing K.

Referring to Fig. 3 there is illustrated one unit or group of devices along the track for controlling the speed of a train at that point, there being any desired number of these units used throughout any given portion of the entire railway. Each of these units comprises a treadle T mounted adjacent to one of the track rails 2 upon parallel links d5 pivoted to supports 46 which are secured to the ties 3. The treadle is formed with a socket 47 in which is loosely fitted the upper end of a vertically movable rod a8, and the lower end of said rod is connected to a piston 49 which fits air-tight in a dash-pot cylinder 50, there being a small restricted orifice 51 in said piston 49. In the bottom of the dash pot cylinder 50 is an opening which is covered by a spring pressed flap valve 52 of suitable construction which permits air to be expelled from the cylinder 50 during downward movement of the piston 19 but which prevents air entering the cylinder 50 through said opening during upward movement of said piston. lnterposed between the bottom of the cylinder and the piston 40 is a compression coil spring which serves to press the piston 4 9 and the rod 4:8 upward. Carried by the rod is a contact member 54; which is adapted to make electrical contact with a spring 55 fixed to a suitable insulating support 56 when the treadle 'l is depressed and the rod '13 forced to its lowered position.

The normal direction of trafiic over the stretch of track shown in Fig. 3 is from left to right in the direction indicated by the arrow X, and located at a predetermined point in advance of the treadle T is a trip G secured to rock shaft 57 journaled in suitaldc supports 58 fastened to one ol': the lies 3. this trip C being arranged so that when in its upper position it engages the valve operating arm 9 on a passing vehicle, as will be clearly understood by those skilled in the art of railway signaling. Fi\,d to the shaft 57 is a lever 59 which carries at one end a weight 60 tending to hold the-trip C in its vertical or stopping position, and which is secured at its other end to a vertically movable rod 61, the lower end of which constitutes the core of two solenoids G2 and 63. I ssociated with the rod 61 is a suitable timing mechanism M which is so constructed and. arranged as to permit said rod to be moved to its upper position shown in Fig. 3 quickly but which requires that a certain time shall elapse before the rod 61 is moved from this upper position to its lower position in which the trip C will clear the valve arm 9 on a passing vehicle. As shown in Fig. 3 this timing mechanism M comprises two gears 6st and 65 secured together and rotatably mounted on a suitable fixed stud 66, the smaller gear Gl being in mesh with teeth formed along one edge of the rod 61. The larger gear 65 meshes with a gear 67 revolubly mounted on a fixed bearing pin 68; and loosely mounted on said bearing pin (38 is an escapement wheel 69 which carries a pivoted pawl 70 pressed by a spring 71 into engagement with the teeth of the gear 67. J2 pallet 7 2 is pivotally mounted on a fixed pin 73 in position to cooperate with the teeth of the escapement wheel 69, said pallet 7 2 being provided with an adjustable weight 7%.

The treadle T and the trip C, together with their associated parts hcreinbefore described, constitute means for preventing a train exceeding a predetermined speed at the place along the track where these devices are located. In many cases, however,

nseneea it is desirable to make provision for per mitting a train to pass a given place along a track at two diiierent speeds, one of these speeds being permissible when there is no train immediately ahead and the only necessary restriction upon the speed of the train is that required by fixed hazards, and the other speed being desired when there is an other train immediately ahead. These two different speeds may be obtained in ditlerent ways, but in the arrangement shown in Fig. 3 another trip P is located at a predetermined point in advance of the treadle T and is fixed to a rock shaft in the same way as the trip C so that it may be moved out of the position shown in Fig. 3 to a lower position in which it will not engage the valve arm 9 on a passing train. Secured to the rock shaft 75 is a counterweighted lever 7 6 which is connected to a rod 7? operable by a solenoid 78, the rod 77 being provided with a timing mechanism M in the same way as in the case of the trip C.

in Fig. t there is diagrammatically illustrated a stretch of track equipped with the system embodying the invention, and the track rails 1 and 2 are divided by insulating joints 79 into track circuit blocks, two complete blocks l3 and C being shown and the adjacent ends of the adjacent bloclrs A and D. Connected across the track rails 1 and 2 at one end of each block is a track battery 80 and connected across said track rails at the other end of each block is a track relay, the track relays tor the blocks C and D only being shown and being designated 31 and 82. Associated with each block is a contact rail or ramp H which is arranged in pcsition to cotiperate electrically and mechanically with the contact shoe carried by the train as more fully explained hereinafter. Throughout the blocks B and C are shown a number of units or groups of devices such as are shown in detail in F 3, there being any number of these units in a given length of track as may be desired. in a above the diagrammatic illustration of the railway track are shown a series of curves of permissive speeds for the blocks B and C. These curves are drawn according to the well known method of plotting curves to rectangular coordinates and in these curves horizontal distances represent to any arbitrarily chosen scale distance along the track, and vertical. distances represent to some arbitrarily chosen scale (as indicated by the figures at the letthand of Fig. 1) speed in miles per hour or other units. At the upper part of Fig. 4 there are shown two rows of F BT69, and these figures are examples of n tree such as carried by the continuous band 20. The upper row of figures inclicates in miles per hour or other suitable units, the permissive speed for the train at different points in its travel under proceed conditions, that is, when there is no other train immediately ahead in the next block; and the lower row of figures indicates permissive speeds at diii'erent points in the travel of the train under caution conditions, that is, when the next block in advance is occupied by another train.

Operation Assume that a vehicle equipped with the apparatus as shown in Figs. 1 and 2 occupies the block A in Fig. 4E and is about to enter the block B, and further assume that there is no other train at any part of the trackway shown in Fig. 1-. The normal condition of the relay 31, under proceed conditions, is energized, the circuit for ener izing said relay being traced as follows: %see Fig. 1) commencing at the battery 90, conductors 91 and 92, relay 31, conductors 93 and 9 1, armature 30 of said relay in its upper position, conductor 95, contact lever 36, spring 39 and conductor 96 back to the battery 90. The relay 31 being energized moves the shutter 25 to cover the lower opening 22 in the casing K thereby exposing the upper row of figures on the continuous band 20. The-speed at which the vehicle is traveling at the time is indicated by the pointer 14!: oi? the speedometer 13, and the proper or permissive speed for the train is indicated by the number on the band 20 appearing opposite the pointer 40.

When the vehicle reaches the ramp it, the plunger 33 is raised to its upper position and moves the outer end of the contact lever 36 downward to break the circuit hereinbefore traced for normally energizing the relay 31. Since it is assumed that no train occupies the block C at this time the track relay 81 is energized and the armature 9'? is in its upper position, thereby applying to the line wires 98 and 99 the voltage of the bat tery 100. The line wire 93 is connected to the track rail 1 oi the block A and the line wire 99 is connect ,d to the ramp it at the entrance to the block B so that difference of potential exists between said ramp and said track rail. At the same time that the plunger 33 of the contact shoe on the vehicle is lifted by engagement with the ramp lit. electrical contact is made between said plunger and the ramp it, vhereupon current may be supplied from the battery 190 to the relay 31 on the vehicle to maintain said relay energized, the complete circuit being traced follows: commencing at the battery 100, line wire 99, ramp it, plunger 33, conductors 103 and 93. relay 31. conductors 92 and 10 1 to the axle 6, thence by the wheels to the track rail 1, line wire 93. armature 97 of the track relay 81 in its upper position and back to the battery 109. In this way, although upon engagement of the contact shoe on the vehicle with the ramp it the circuit for normally energizing the relay 31 is interrupted, current is supplied from the battery 100 along the track to said relay to maintain it energized, and this substitute current maintains the relay 31 energized so long as the contact shoe remains in engagement with the ramp R and until contact shoe returns to its normal position shown in. Fig. 1. so as to permit the closing of the normally closed circuit of said relay. Consequently, when a difference of potential exists between the ramp R and the track rail, the relay 31 is not affected, and the shutter 25 remains in its lower position leaving exposed the figures indicating the proceed permissive speeds.

Suppose, however, that when the vehicle in question passes the ramp It the block C is occupied by another train. The wheels and axles of this other train in the block C deenergize the track relay 81 and cause its armature to assume its lower position, thereby interrupting the circuit by means of which a difference of potential is established between the ramp It and the track rail. Consequently, when the contact shoe and the vehicle engage the ramp R, the relay 31 is deenergized since the raising of said contact shoe interrupts the circuit normally keeping said relay energized and since no substitute current is supplied to said relay. When the relay 31 is deenergized its armature 3O falls by its own weight to its lower' position thereby opening another break in the circuit hereinbetore traced for normally energizing said relay, so that when the contact shoe leaves engagement with the ramp it and permits the contact lever 36 to again engage the spring 39, nevertheless the normally closed circuit for the relay 31 is not established, and cannot be established until the relay 31 is energized by the current supplied from the trackway. The dropping off the armature 30 of the relay 31 moves the bar 27 downward and by means of the gear 26 and the shaft 24 swings the shutter 25 from its lower position shown in Fig. 1 to its upper position. In this way the figures indicating the proper permissive speed under proceed conditions are covered by the shutter and the figures indicating permissive speeds under caution conditions are ex posed.

From the foregoing it can be seen that means is provided by this invention for indicating on a train or vehicle the proper permissive speed therefor at diticrent points in its travel under proceed conditions or under caution conditions; and it is easy for the engineer to compare the actual speed ot the train as shown l. y the speedometer 13 with the permissive speed of the train and determine in this way how to control the movements of his train. The continuous band 20 advances as the vehicle progresses and as the figures on said band come successively under the pointers 40 and 41 there is indicated the proper permissive speed for the vehicle at the point along the track where it is then located. It may be dillicult to cause the movement of the continuous band 20 to accord exactly with the travel oi' the vehicle at all times due to inarcnrzmies and variations in construction, the wearing of the wheels, and the like, and hence provision is made by the thumb-nut l3 and the threaded rod 4A for enabling the engineer to adjust the pointers 40 and to correspond with marks on the band 20 at certain known points along the railway, preferably at stations and like points where the vehicle ordinarily comes to a stop.

Referring to Fig. 4 the curve 8- drawn as a heavy line is the curve of permissive speed for a train in the block B under raution conditions, that is, when a train occupies the next block C in advance. This curve 8% is derived from the braking curve for the grade or grades of the portion oi? the track included in the block B. This curve of permissive speed Set indicates for the dii ferent points in the travel of the train tne highest speed which the train may have at these points and yet by a prompt application of the brakes. be brought to a stop or to a predetermined low speed, before reaching the end of the block B. The lower row of figures on the band 20 shown in Fig. 4 are the permissive sgeeds determined by the curve St at difterent selected points along the length of the block B, the location or number of these points being arbitrarily chosen as desired. In the same way the curve 85 indicates the permissive speeds under caution conditions for diiierent points in the travel. of the train through the block C. In order to illustrate the adaptability ot' the system embodying this invention to one of the conditions which may be met with in practice the block C is made shorter than the block B; and since the block C is shorter than the block B the speed at which a train may enter the block C and yet be brought to a stop by an up plication of the brakes is less than the speed at which a train may enter the block 13, tor the reason, which will be apparent to those skilled in the art of braking trains, that the braking distance of a train depends upon its speed and is longer the higher the speed. When a train enters the block C it may well happen that the next block in advance, D, is occupied by another train and it will be necessary for the following train in the block C to reduce its speed and come to a stop or to a predetermined low speed by the time it reaches the end of the block G; and as pointed out hereinbeiore to accomplish this it is necessary that the following train should not enter the block C at a higher speed than that indicated by the curve of permissive speed 85 at the entrance to the block 0, this permissive speed being also indicated by the horizontal dash line 89. Consequently it can be seen that, since the train may enter the block l3 at the comparatively high speed indicated by the dash line 86 and must enter the block G at a speed not exceeding the lower speed indicated by the dash line 89, it is necessary to compel a reduction in speed while the train is in the block B. This reduction in the speed of the train in block B so that it may not enter the block C at too high a speed is indicated by a dash line 88 which is derived from the braking curve 01? the train for the portion of the block B tending from the point 87 to the end of that block, the curves 88 and 85 constituting a continuous curve of permissive speed from the high speed indicated by the dash line 86 to zero speed at the end of the block C. From this it can be seen that even though. a train is traveling under proceed conditions it must commence to reduce speed after leaving the point 87 part way in the block B, and this fact is indicated to the engineer by the decreasing figures in the upper row on the continuous band 20 as can be seen in Fig. 4:.

A vehicle or train is compelled to observe the limiting permissive speeds hereinbefore explained at different points in the blocks B and C by the operation 01. the units or groups of control devices such as shown in Fig. 3, and since the operation of each of these units is the same the description of the operation of the unit shown in Fig. 3 will suffice for all. Referring to Fig. 3, assume that a train is traveling from left to right in the normal direction of trailic indicated by the arrow X and that there is no train immediately ahead in the next block in ad* vance so that the track relay, as the relay 81, connected to said block, is energized. The track relay 81 being energized causes an energization of the solenoid 63 associated with the trip C, since the voltage applied to the line wires 98 and 99 by the battery 100 may flow along conductors 101 and 102 through said solenoid 63; and consequently the trip C is drawn down to its lower position in which it does not engage the valve arm 9 on a passing train. When the first pair of wheels of the vehicle reach the treadle T, this treadle T is depressed against the opposition of the spring 53 and the contact piece 5a is brought into electrical contact with the spring 55 thereby closing a circuit for energizing the solenoid 78 controlling the trip P by current flowing along a circuit which may be traced as follows: commencing at the battery 106, conductor 107, contact piece 5%, spring 55, conductors 108 and 109, solenoid 78 and conductors 110 and 111 back to the battery 106. The solenoid 78 being energized pulls the rod 77 downward and causes a gradual movement of the trip P from its upper stopping position to its lower clear position, and due to the timing mechanism M this movement of the trip P to its clear position requires a certain amount of time. if the vehicle in question is traveling at such a speed that after leaving the treadle T it reaches the trip before the time required to move the trip P to its clear position has elapsed, the trip P strikes the valve arm 9 and opens the valve 8 and causes an automatic application of the brakes. On the other hand, if the train is traveling at such a speed while traversing the space between the treadle T and the trip P so that it occupies more than the time required for the trip P to move to its clear position, said trip will be clear by the time the train reaches it, and will not operate to cause an application of the brakes on the vehicle. It can be seen that by varying the distance between the treadle T and the trip P or by varying the time required to move the trip P to its clear position any de sired limiting speed for the vehicle may be established, since the time required for the vehicle to travel a given interval of distance is a measure 0rits speed The dash-pot cylinder 50 and its associated parts are shown as illustrative of a means for holding the contact member 54 in contact with the spring 55 so as to keep the solenoid 78 energized for a time suiiicient to permit the train, when traveling at the ordinary speed, to proceed to a point where the valve arm or arms 9 carried thereby are past the trip P. In other words, the time of return movement of the dash-pot device, in connection with the length or". the treadle T, is so selected as to keep the solenoid 78 energized and the trip P down in its clear position after said trip has assumed its clear position long enough to permit the train to get by the trip P without being stopped. In this connection it should be noted that the circuit for energizing-the solenoid 78 can be broken only when the treadle T is not pressed. down by the wheels of a train, and the treadle T may be made of such length and so positioned that it will always be depressed until the train has passed the trip P.

Assume a train traveling from left to right in the direction of trailic indicated by the arrow X over the stretch of track shown in Pig. 3 and assume that the next block in advance controlling the track relay 81 is occupied by another train. Under these conditions the circuit for energizing the solenoid 63 is broken at the armature 97 of the track relay 81, so that the trip C is in its upper position as shown in Fig. 3. When the vehicle passes the treadle T, the solenoid 62 of the trip C is energized by a circuit which may be traced as follows? Commencing at the battery 106, conductor 107, contact piece 5 1, spring 55, conductors 108 and 112, solenoid 62, and conductors 113 and 111 back to the battery 106. The solenoid 62 being energized, moves the trip 0 gradually to its clear position, and it the train at that time is traveling at such a speed that it occupies more than this time in passing from the treadle T to the trip C, no application of the brakes will result; but on the contrary if the train, in traveling from the trea-dle T to the trip C, consumes less than the time required to move the trip C to its clear position, an automatic application of the brakes will result. Since the distance between the treadle T and the trip C and the time required to clear the trip C is such as to compel the train to travel at a lower speed than it is compelled to travel in passing over the distance from the treadle T to the trip P, it can be seen that, since the train must have observed the speed limitation imposed by the trip C, the trip P will be in its clear position by the time the train reaches it.

In Fig. 5 there is illustrated in the same manner as in Fig. 4; other ways in which the systems embodying this invention may be adapted to conditions occurring in the application of the speed control system to practical railroad conditions. The block F in Fig. 5 is assumed to represent a condition where a sharp curve, or other fixed hazard, near the exit end of the block requires that the speed of the train should be reduced in the first part of the block F irrespective of whether or not the next block G in advance is occupied by a train. The comparatively low speed which the train should not exceed in passing the fixed hazard is indicated by the dash line 114, and the curve 115 indicates the different permissive speeds which the train should be compelled to follow either under proceed or caution conditions. It is noted that since the permissive speeds in the first part of the block F are the same under caution conditions as under proceed conditions, it is necessary to have only one trip P in each unit ,for this part of the block. The curve 116 represents the permissive speeds which the train should be compelled to follow when the next block G in advance is occupied by another train. The distance for which the comparatively low speed limitation indicated by the line 114 should be used is determined by the physical characteristics of the block E, the nature and extent of the fixed hazard, and may be of any length desired. For example, if the fixed hazard is a sharp curve, it may be necessary to make the distance over which the train must travel at the lOW speed indicated by the line 114: such that a train of the usual length would be entirely past the sharp curve before it would be permitted to attain a higher speed.

The dash line 117 represents the permissive speed which the train should be permitted to attain after passing through the region where the low permissive speed required by the fixed hazard occurs, and this line 117 is derived from the speed-distance curve of acceleration of the train.

The block G in Fig. 5 represents the condition where the maximum permissive speed for the train under proceed conditions may for some reason be less than the speed at which a train might enter the block (i and yet be brought to a stop by an application of its brakes before reaching the end 01' said block, that is, the length oi? the block Gr corresponds to the breaking distance of the train for a higher speed than the speed (indicated by the line 117) which it is desired to prevent the train from exceeding while passing through the block G under proceed conditions. The curve 119 indicates the permissive speeds which the train should be compelled to follow in the block G under caution conditions.

From the foregoing explanation it can be seen that there is provided by this invention a system for automatically controlling the speed of railway trains by means of which the speed of the train may be controlled at different points in its travel either in accordance with fixed hazards or in accordance with movable hazards. The device by means of which the speed of the train under proceed conditions is limited can be adjusted and regulated separate from the devices for imposing a speed limitation under caution conditions, and consequently any desired speed at any desired point in any block may be obtained for proceed conditions irrespective of what the permissible speed under caution conditions is. As is well understood by those skilled in the art of braking trains, the distance in which a train may be brought to a stop by an application of its brakes not only varies with the speed, but also with certain physical characteristics of the track over which the train is traveling, as grades. curves and the like; but by properly selecting the space and time intervals for the difierent units a proper speed limitation for any point along the railroad may be obtained, so that regardless of whether or not the blocks are of different length, or are of different grades. in whole or in part, it is possible to obtain a proper control of the speed of the train over these blocks. The engineer 'or motorman of the train is advised during the progress of the train what the limiting speed is, also what the actual speed of the train is, and consequently, the engineer may readily determine how he should govern the train for safety and for the best facility. In the particular embodiment of the invention shown and described the permissive speeds for the train at different points in its travel are indicated on the train by numbers on the continuous band 20, but obviously other means for accomplishing the same result could be used, and the variations in the permissive speed may be indicated to any desired degree of refinement. It should be clearly understood that the use of the continuous band and the indication of the permissive speeds given thereby is not essential to the proper control of the speed of the train and is used in order to aid the engineer in governing his train to obtain the greatest facility with safety; and in some cases it may be found expedient to dispense with this continuous band. The movement of the shutter 25 informs the engineer whether or not there is another train in the next block in advance, and consequently this shutter takes the place of cab signals or fixed signals along the right of way, although cab signals or fixed signals may be used if desired. The adjustment of the means used for indicating permissive speeds on a train is shown in the embodiment of the invention illustrated ob tained in a simple manner by adjusting the pointers 40 and 41 manually at predeten mined reference points along the track, but it is apparent that the same result could be accomplished automatically.

Referring to Fig. 3, it can be seen that each unit or group of devices for imposing a speed limitation upon a passing train, broadly considered, consists of a trip or other impulse device capable of causing an automatic application of the brakes, a treadle or other impulse device which is set into operation by the movement of the train past the point where said treadle or impulse device is located, a suitable timing mechanism associated with the trip or equivalent impulse device which acts to render said trip or impulse device ineifective to cause an automatic application of the brakes after the lapse of a predetermined time following the initial operation of the treadle or equivalent impulse device. In the embodiment of the invention illustrated the mechanism capable of accomplishing these functions has been shown in its simplest form and obviously many variations might be made in the manner of obtaining the impulses from the track to the train and in the timing of the operation of the parts without departing from the invention. The treadle T and the trips C and P may be, and preferably would be in practice, some form of an inductive impulse device capable of transmitting a controlling impulse between the track and the train. without physical contact, although contact shoes and ramps, or other impulse devices may be used. The variations in the speed limitations imposed by the different unitsmay be obtained either by changing the distance between the treadle or initiating impulse device and the trip or brake controlling impulse device, or the same variation in the speed limitation may be obtained by varying the time of operation of the timing mechanism. It can also be seen that difierent speed limitations may be obtained with a single treadle and a single trip by varying the time of operation of the timing mechanism. ltshould be noted that it is not always necessary in the different blocks to use the trips P for imposing a speed limitation upon a train under proceed conditions because on certain parts of the railroad the safe speed which a train may travel under proceed conditions may be as high or higher than the speed which the train might attain in any event under its own power. lln illustrating the application of the invention to certain conditions found in practice in i and 5 no attempt has been made to show precisely the location of the trips and treadles or the exact distances between them, nor are the figures indicating permissive speeds intended to be exactly accurate, but are merely illustrative.

Each unit acts to cause an automatic ap plication of the brakes if the average speed of the train in passing over the space between the initiating treadle and the corresponding trip exceeds a certain value, and it can be seen that it is possible for a train to enter this space at a comparatively low speed and accelerate to a higher speed while traveling over the space and yet not exceed the average speed prescribed by the controlling unit; but compensation is made for this possible action of the train when detor-mining the distance between the treadle and the trip and the time of operation of the trip such that even if the train should increase its speed while traveling over the space between the treadle and the trip it could not at the time it reached the trip be exceeding the speed which would prevent it being brought to a stop by an application of the brakes by the time it reached the end of the corresponding block.

Although I have particularly described the construction of one physical embodiment of my invention, and explained the operation and principle thereof; nevertheless, ll desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical embodiments of the idea of means underlying my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. ln an automatic train control system, in combination: a vehicle and a track there for divided into blocks; a safety appliance for the vehicle; a plurality of means located at a numl'ier of points in each block and having their influence upon the safety appliance determined by the rate of movement of the vehicle at these points; and means on the vehicle for indicating to the operator thereof the existing relation between the actual rate of movement of the vehicle and that required by said trackway means.

2. In an automatic train control system, in combination: a vehicle and a track therefor divided into blocks; a safety appliance for the vehicle .and a plurality of means including time controlled devices and located at a number of different points in each block for operating said appliance; each of said means being controlled by the vehicle and acting to cause operation of the safety appliance when a predetermined interval of distance at that means is traveled by the vehicle in less than a predetermined interval of time.

3. In an automatic train control system, in combination: a vehicle and a track therefor divided into blocks; a safety appliance for the vehicle; a plurality of impulse devices located at a number of different points in each block and each acting under dangerous trafiie conditions to operate said safety appliance When an interval of distance at the corresponding point is traveled by the vehicle in less than a predetermined time; and means on the vehicle for indicating to the operator thereof the existing relation between the actual speedof the vehicle and the limiting speed required by said track- Way impulse devices.

4. In an automatic train control system, in combination: a vehicle and a stretch of track therefor at least as long as brakin distance for the vehicle at the highest speed it can enter said stretch; and means comprising time controlled elements along the track cooperating With a brake-setting mechanism on the vehicle and having a tendency to cause an automatic application of the brakes of the vehicle if it travels any one of succeeding predetermined intervals of distance along said stretch in less than predetermined intervals of time.

5. In an automatic train control system, in combination: a vehicle and a track therefor; means at different points along the track for preventing the vehicle from travcling at these points a predetermined dis tance in less than a predetermined time; and traflic controlled means for governing said means to vary the time-distance interval associated therewith.

6. In an automatic train control system, in combination: a vehicle and a track therefor; a safety appliance for the vehicle; means for operating said safety appliance at different points in the travel of the vehicle if a predetermined interval of distance at that point is traveled by the vehicle in less than a predetermined time; other means for operating said safety appliance at different points in the travel of the vehicle if a predetermined interval of distance at that point is traveled by the vehicle in less than a predetermined time; and means for selectively controlling said means.

7. In an automatic train control system, in combination: a vehicle and a track therefor divided into blocks; a safety appliance for the vehicle; a plurality of impulse devices located at different points in each block for controlling said appliance; means associated with each impulse device for rendering it ineffective to control said appliance after the lapse of a predetermined time, and means associated with each of said last mentioned means and responding to the passage of the vehicle for initiating the operation of said last mentioned means at a predetermined distance in the rear thereof.

8. I11 an automatic train control system, in combination: a vehicle and a stretch of track therefor; mechanism for retarding the movement of the vehicle; and a plurality of means along the track controlled successively by the passage of the vehicle for operating said mechanism when. said vehicle travels over any one of succeeding n'edetermined intervals. of distance in less than predetermined intervals of time, the quotient of successive intervals of distance and time decreasing along said stretch of track.

9. In an automatic train control system, in combination: a vehicle and a track therefor; means for retarding the movement of the vehicle if it travels any one of a plurality of succeeding intervals of distance in less than succeeding predetermined intervals of time, thereby limiting the speed of the vehicle to succeeding prescribed permissive speeds; and means for indicating on the vehicle said succeeding permissive speeds therefor.

10. In an automatic train control system, in combination: a vehicle; a track for the vehicle divided into track circuit blocks; means for indicating on the vehicle as it travels the differing permissive speeds therefor throughout the length of the track both under proceed conditions and under caution conditions; and means controlled by the track circuits of said blocks for governing said means to select Whether the proceed permissive speeds or the caution permissive speeds are indicated.

11. In an automatic train control system, automatic speed control apparatus for railway vehicles comprising a permissive speed indicator including a continuous band driven from the Wheels of the vehicle and adapted to indicate either of two series of permissive speeds for the vehicle during its travel, one series corresponding to clear and the other to dangerous traiiic conditions ahead, manually operable means for permitting adjustment of said permissive speed indicator to conform With the location of the vehicle,

nearest and trailic controlled means partly on the vehicle and partly along the track for governing the said speed indicator to selectively determine the series of permissive speeds to be indicated.

12. lln an automatic train control systenn in combination: a vehicle and a traclr therefor divided into blocks; a safety appliance for the vehicle; trackway means associated with each bloclr for operating said appliance when. the vehicle exceeds a predetermined permissive speed at different points in its travel in said block; carried by the vehicle and capable of indicating the permissive speeds therefor during its travel through the several blocks; and means for controlling said last mentioned means in accordance with the movement of the vehicle along the track to select the indication of permissive speed corresponding to the existing location of the vehicle.

13. In an automatic train control system, in combination: a vehicle and a track therefor divided into blocks; a safety appliance for governing the movement of the vehicle; impulse devices located at a number of points in each block for controlling the speed of the vehicle in each block when the next block in advance is occupied, said im pulse devices tending to assume an active condition and cause operation of said appliance upon passage of the vehicle thereby; means effective upon the approach of the vehicle to a point a predetermined interval of distance from each of the impulse devices for causing that device to assume its inactive condition after the lapse of an interval of time; and means for causing all of the impulse devices of a block to assume their inactive condition when the next block in ad vance is not occupied.

14. in an automatic train control system in combination: a vehicle and a track therefor divided into blocks; a safety appliance for governing the movement of the vehicle; a plurality of impulse devices located at a number of different points in each block and each having a tendency to assume a stopping condition, thereby tending to cause operation of the safety appliance upon a passing vehicle; mechanism associated with each impulse device and adapted when set into operation to cause said impulse device to assume its non-stopping condition after the lapse of an interval of time; and means located at a predetermined distance in the rear of each impulse device and responding to the passage of a vehicle thereby for initiating the operation of the corresponding mechanism. v

15. In an automatic train control system, in combination: a vehicle and a track therefor divided into blocks; means for limiting the speed of the vehicle prior to its entrance to each block to accord with the length and physical characteristics of that block; and means partly on the vehicle and partly distributed along each block for retarding the movement of the vehicle at successive points in each block whenever it travels any one of a number of successively decreasing intervals of distance in less than a fined interval of time.

16. In an automatic train control system, in combination: a vehicle and a track therefor; a brake controlling appliance on the vehicle; a proceed impulse device and a caution impulse device along the track having a tendency to cause operation of said appliance upon passage of the vehicle thereby; mechanism associated with each device for causing it to assume its inactive controlling condition after the lapse of an interval of time; and means at varying distances in the rear of said impulse devices and responding to the passage of the vehicle thereby for initiating the operation of the corresponding mechanism.

17. 111 an automatic train control system, in combination: a vehicle and a track therefor divided into blocks, the length of each block being separated into intervals of distance which decrease from the entrance end of the block to the exit end in accordance with a predetermined curve of speed restriction; a brake setting impulse device disposed at the advanced end of each interval of distance and tending to assume an active condition; means set into operation upon the passage of the vehicle by the rear end of each interval of distance for causing the corresponding bralre setting impulse device to change to its inactive condition after the lapse of a predetermined time; and means for rendering all of the brake setting impulse devices of each block inactive when the next block in advance is not occupied, whereby the brakes of the vehicle will be automatically applied at any one of a number of successive points in each block when the next block in advance is occupied unless the vehicle takes more than a predetermined time in traveling over successively shorter intervals of distance.

18. lln an automatic train control system, in combination: a vehicle and a track therefor divided into blocks, said track having a long block followed by a short block; means on the track distributed along each block for automatically imposing decreasing speed limitations on the vehicle during its progress through that block when the block next in advance is occupied; and means on the track for automatically imposing a decreasing speed limitation on the vehicle during its progress through the latter part of the long block to conform with the permissible entrance speed into the short block, irrespective of whether or not the short block is 00- cupied by another train.

19. In an automatic train control system,

in combination: a vehicle and a track therefor divided into blocks, said track having a long block followed by a short block; means for imposing a decreasing speed limitation on the vehicle during its progress through each block whenever the next block in advance is occupied; and means on the track distributed over part of the long block for compelling the vehicle to take more than a predetermined interval of time in traveling over each of successive intervals of distance irrespective of traflic conditions in the short block in advance, whereby the vehicle will be automatically compelled to reduce its speed prior to its entrance to the short block so as to conform with the maximum entrance speed permitted by the length of the short block.

20. In an automatic train control system, in combination: a vehicle and a track therefor; a permissive Speed indicator comprising a continuous band driven by the wheels of the vehicle and adapted to give either of two limiting speeds for the vehicle at different points in its travel, said limiting speeds corresponding respectively to safe and dangerous traiiic conditions in the next block in advance; an automatic means controlled in accordance with trailic conditions for'selectin-g the limiting speed to be given by said indicator in accordance with traiiic conditions in said next block in advance.

21, In an automatic train control system for railroads having tracks divided into blocks each provided with a normally closed track circuit, apparatus for compelling a reduction in the speed of vehicles traveling through a block when the next block in ad- Vance is occupied, comprising, in combination, a plurality of electrically operable impulse devices located at intervals in the bloclrand having a tendency to assume a stopping condition, time-controlled mechanism associated with each impulse device and adapted when set into operation to change that-device from its stopping condiion to its non-stopping condition after the lapse ofa predetermined interval of time,

meanscontrolled by the track circuit of the next block in advance for placing said impulse devices in-the non-stopping condition, and circuit controlling means located at a distance in the rear of each impulse device and responding to the'passage of the vehicle thereby :torinitiating the operation of the corresponding time-controlled mechanism, whereby the vehicle is required to take more than a predetermined interval of time intraveling over successive intervals of distance when the next block in advance is occupied, in order to avoid being influenced by said impulse devices in their stopping condition. 7 I h 22. In an automatic train control system for railroads divided into blocks, the combination with a vehicle and a brake control.-

ling appliance thereon, oi: a number of impulse devices distributed along the track and effective at times to cause operation of said appliance, time controlled means asso iated with said d'evi "as and influenced by the passage of a vehicle for changing the controlling condition of said devices alter the lapse of a corresponding interval oi time, and traiiic controlled means for indcpciulcniiy governing said impulse devices, said devices and time controlled means acting to enforce diiiercnt restri -tions upon the speed of the vehicle at predetermined points in its travel through a blocl: under either safe or dangerous traiiic conditions in a block in ad- "vance.

23. In an automatic train control system tor railroads having tracks divided into blocks of varying length, the combination with a vehicle and a b 'alte control appliance thereon, of means including a plurality of impulse devices distributed in each block and causing operation of the brake setting appliance on a passing vehicle, each impulse device having its operating influence upon said appliance determined by a corresponding rate of movement oi? the vehicle thercat,

' I. devices thereby acting to enforce predetermined speed limitations for the vehicle at a number of control points in a block which limits vary to conform to a braking curve for that block, and traflic controlled means for rendering said impulse devices ineffective under safe trafiic conditions.

24. In an automatic speed control system for railroads having tracks divided into blocks, a plurality of trackway devices in each block adapted to exert an influence on a passing .vehiole dependent upon the rate of movement of the vehicle thcreat, means for governing said devices in each block in accordance with trai'lic conditions in the next block in advance, and similar trackway devices t'or enforcing speed limits near the entrance to each block to conform with the maximum permissive entrance speed for that block.

25. In an automatic train control system for railroads having fixed hazards where low speed limits should be enforced, the combination with a vehicle and a brake control appliance theron, of means including a plurality of permanently active track devices each capable oi causing operation of said appliance dependent upon the rate of movement of the vehicle at such device, said means acting automatically to compel a rcduction in speed of the vehicle step by step from a maximum speed to a predetermined low speed suitable for the hazard.

26. Automatic train cont-1'01 apparatus for railway vehicles comprising, means driven continuously from the wheels of the vehicle and adapted to give either of two limiting speeds corresponding to safe and dangerous traflic conditions ahead, said means being adjustable to conform to the location of the vehicle, and trafiic controlled means for automatically selecting the limiting speed to be iven by said means.

24. Automatic train control apparatus for railway vehicles comprising, a speed responsive device operated from the Wheels of the vehicle in accordance With its instantaneous actual speed, permissive speed means continuously driven from the Wheels of the vehicle for giving either of two series of permissive speeds, means for selecting one or the other of said series, and a stick relay controlled from the track for governing said last mentioned means.

28. In an automatic train control system, a trackWay impulse device having a tendency to assume its stopping condition, electrically operable means including time controlled mechanism and adapted When energized to change said impulse device from its stopping to its non-stopping condition after the lapse of a predetermined interval of time, and tWo separate circuits for energizing said device, one controlled by traflic conditions ahead and the other by a vehicle as it approaches said device.

LYMAN E. DODGE. 

